In today’s Academic Minute, Dr. David Wilkinson of Liverpool John Moores University examines the role methane may have played in warming the Earth during the time of the dinosaurs.
David Wilkinson is a Reader in Environmental Science at Liverpool John Moores University. He is a generalist with wide interests within biology, environmental science, archaeology and the history of science. He is currently engaged in theoretical work on ecology and evolution. He holds a Ph.D. from Manchester Metropolitan University.
Dr. David Wilkinson – Dinosaurs and Methane
Say ‘global warming’ and the gas that usually comes to mind is carbon dioxide. However methane is also a potent greenhouse gas and just as humans have affected the amount of carbon dioxide in the atmosphere, we have also caused an increase in methane -one source being the microbes that live in the guts of out livestock and which help them digest their food.
Recently with my colleague Graeme Ruxton I have become interested in the biology of sauropod dinosaurs. These are the huge, long-necked, dinosaurs that could be over four times the weight of a large elephant. It occurred to us that if modern cattle can potentially be a source of climate altering amounts of methane then those extinct giants could have been an important source of greenhouse gasses in the past.
It was an intriguing possibility, but how do you calculate the amount of methane produced by long extinct animals? It turns out that there are equations which describe how methane production by modern plant eaters is related to their body size. We used these to make an informed guess about the likely methane output of a large sauropod. Other scientists had estimated the biomass – that is the weight of sauropods – that might have been found living on a given area of land. Taking these figures we estimated global methane production by sauropods and – with the help of Euan Nisbet – worked out what this implied for methane levels in the Earth’s atmosphere.
Our result is obviously an educated guess – but to our surprise the answer is extraordinary! The methane output of these dinosaurs may have been equivalent to total amount of methane produced on Earth today – from both natural and man-made sources! We know the climate of the time was very warm and that some sort of greenhouse effect is the likely explanation for this; could methane from dinosaurs have been one of the reasons for this?